This invention relates in general to clutches and in particular to a friction clutch having rotatable friction rings mounted respectively on the flywheel and the pressure plate for engaging a driven disc assembly therebetween.
Clutches are well known devices which are frequently employed in vehicles to selectively connect a source of rotational power, such as the crankshaft of an engine, to a driven mechanism, such as a transmission. Typically, a cover of the clutch is connected to a flywheel carried on the end of the engine crankshaft for rotation therewith. Between the flywheel and the clutch cover, a pressure plate is disposed. The pressure plate is connected for rotation with the flywheel and the cover, but is permitted to move axially relative thereto. A shift lever assembly is provided for selectively moving the pressure plate back and forth in the axial direction.
A driven disc assembly is disposed within the clutch between the pressure plate and the flywheel. The driven disc assembly is carried on an output shaft of the clutch, which is also the input shaft to the transmission. When the pressure plate is moved toward the flywheel, the driven disc assembly is frictionally engaged therebetween so as to cause the output shaft of the clutch to rotate with the flywheel, the cover, and the pressure plate. In this manner, the clutch is engaged to transmit power from the engine to the transmission to drive the vehicle. When the pressure plate is moved away from the flywheel, the driven disc assembly is released from such frictional engagement so as to disconnect this driving connection. The clutch is typically disengaged to permit a gear shifting operation to occur within the transmission.
The transmission is often provided with a conventional synchronizer mounted on the input shaft thereto. The synchronizer is provided with one or more friction surfaces. When the clutch is disengaged and a shifting operation is about to occur, the synchronizer friction surface engages a corresponding surface formed on a selected transmission gear so as to synchronize the rotational speeds of the input shaft and the selected gear. Such speed synchronization is necessary to prevent undesirable clashing of the gear teeth during the shifting operation. Because of the relatively large inertia of the various rotating gears within the transmission, the synchronizer primarily alters the rotational speed of the input shaft of the transmission to correspond with the rotational speed of the selected transmission gear when a shifting operation is about to occur.
However, as mentioned above, the driven disc assembly is usually mounted on the input shaft of the transmission for rotation therewith. As a result, the inertial load applied to the synchronizer during frictional engagement with the selected transmission gear is determined by the sum of the weight of the input shaft and the weight of the driven disc assembly. Thus, the weight of the driven disc assembly is an important factor in rotational inertia of the driven disc assembly and, consequently, the operation of the transmission. Therefore, to reduce wear on the synchronizer and otherwise improve the overall quality of the shifting operation, it is desirable to maintain the weight of the driven disc assembly at a minimum.